Brissette says that a number of living conditions could affect the eggs’ nutrition, including sunshine, and the inclusion of grass and insects in the hens’ diet, instead of the corn-based diet that many conventionally raised hens eat.

“I would expect some variation based on what the hens are fed,” says Brissette.

While the Marketplace test only looked at a small number of samples, the findings are consistent with other studies that have looked at how farming methods affect nutrition.

One 2010 study from Penn State College of Agricultural Sciences found eggs from hens allowed to forage in pastures are higher than conventional eggs in some beneficial nutrients, including fat-soluble vitamins and omega-3 fatty acids.

These findings make sense. Even if the eggs weren’t going to be determined “better,” it would still make sense that they would have different nutritional data. The chickens are on different diets, so naturally they are going to be exposed to different nutrients.

Free-range chickens still eat grains, but they also munch on insects, worms, grass, and other plant life.

Space and sunshine can also play roles on nutrient levels. By giving the chickens a natural source of vitamin D and by reducing stress, you’re going to end up with a different end product, and in this case, it is a healthier, more nutrient dense egg.